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draft-ietf-opsawg-ipfix-on-path-telemetry-09.xml
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<?xml version="1.0" encoding="US-ASCII"?>
<!DOCTYPE rfc SYSTEM "rfc2629.dtd">
<?rfc toc="yes"?>
<?rfc tocompact="yes"?>
<?rfc tocdepth="3"?>
<?rfc tocindent="yes"?>
<?rfc symrefs="yes"?>
<?rfc sortrefs="yes"?>
<?rfc comments="yes"?>
<?rfc inline="yes"?>
<?rfc compact="yes"?>
<?rfc subcompact="no"?>
<rfc category="std" docName="draft-ietf-opsawg-ipfix-on-path-telemetry-09"
ipr="trust200902">
<front>
<title
abbrev="Export of Delay Performance Metrics in IP Flow Information eXport (IPFIX)">Export
of On-Path Delay in IPFIX</title>
<author fullname="Thomas Graf" initials="T" surname="Graf">
<organization>Swisscom</organization>
<address>
<postal>
<street>Binzring 17</street>
<city>Zurich</city>
<code>8045</code>
<country>Switzerland</country>
</postal>
<email>[email protected]</email>
</address>
</author>
<author fullname="Benoit Claise" initials="B" surname="Claise">
<organization>Huawei</organization>
<address>
<email>[email protected]</email>
</address>
</author>
<author fullname="Alex Huang Feng" initials="A." surname="Huang Feng">
<organization>INSA-Lyon</organization>
<address>
<postal>
<street/>
<city>Lyon</city>
<region/>
<code/>
<country>France</country>
</postal>
<phone/>
<facsimile/>
<email>[email protected]</email>
<uri/>
</address>
</author>
<date day="16" month="July" year="2024"/>
<abstract>
<t>This document specifies new IP Flow Information Export (IPFIX)
Information Elements to export the On-Path Telemetry measured delay on
the OAM transit and decapsulation nodes.</t>
</abstract>
</front>
<middle>
<section anchor="Introduction" title="Introduction">
<t>Network operators usually gather and maintain some forms of
statistical delay view of their networks (or segments of their
networks). That view is meant to help understanding where in the
network, for which customer traffic or services, how much, and why
abnormal delay is being accumulated. To that aim, delay-related data
need to be reported from devices covering both data and control planes.
In order to understand which customer traffic is affected, delay-related
data need to be reported into customer data-plane context. That enables
network operators to quickly identify when the control-plane updates the
current path with a different set of intermediate hops (that is, a
change of the forwarding path) and interfaces, how the path delay
changes for which customer traffic.</t>
<t>With On-Path Telemetry, described in the <xref target="RFC9232">
Network Telemetry Framework</xref> and applied in <xref
target="RFC9378"> In Situ Operations, Administration, and Maintenance
(IOAM) Deployment</xref> and <xref
target="I-D.ietf-ippm-alt-mark-deployment">Alternate Marking Deployment
Framework</xref>, the path delay between two endpoints is measured by
inserting a timestamp in the packet.</t>
<t>At least two modes of On-Path Telemetry can be distinguished.
Passport mode, where only the last hop in the
forwarding path of the On-Path Telemetry domain exposes all the metrics,
and postcard mode, where the metrics are also exposed in transit nodes.
In both modes the forwarding path exposes performance metrics allowing
to determine how much delay has been accumulated on which hop. The
proposal in this document makes more sense for the postcard mode.</t>
<t>In order to export the delay-related metrics via IPIFX <xref
target="RFC7011"/>, this document defines four new IPFIX Information
Elements (IEs), exposing the On-Path delay on OAM transit and
decapsulation nodes, following the postcard mode principles. Since these
IPFIX IEs are performance metrics <xref target="RFC8911"/>, they must be
registered in the <xref target="IANA-PERF-METRIC">"IANA Performance
Metric Registry</xref>.</t>
<t>Following the guidelines for Registered Performance Metric Requesters
and Reviewers <xref target="RFC8911"/>, the different characteristics of
the performance metrics (Identifier, Name, URI, Status, Requester,
Revision, Revision Date, Description, etc.) must be clearly specified in
the <xref target="IANA-PERF-METRIC">"IANA Performance Metric
Registry</xref> in order for the measurement results using the
Performance Metrics to be comparable even if they are performed using
different implementations and in different networks. The first
performance metric characteristic is the selection of a meaningful name,
following the "MetricType_Method_SubTypeMethod_... Spec_Units_Output"
naming convention (See Section 7.1.2 of <xref target="RFC8911"/>).</t>
<t><figure>
<artwork><![CDATA[
+------------------------------------+-------------------------------+
| Performance Metric | IPFIX Information Element |
+------------------------------------+-------------------------------+
|OWDelay_HybridType1_Passive_I |pathDelayMeanDeltaMicroseconds |
|P_RFC[RFC-to-be]_Seconds_Mean (TBD1)|(TBD5) |
+------------------------------------+-------------------------------+
|OWDelay_HybridType1_Passive_I |pathDelayMinDeltaMicroseconds |
|P_RFC[RFC-to-be]_Seconds_Min (TBD2) |(TBD6) |
+------------------------------------+-------------------------------+
|OWDelay_HybridType1_Passive_I |pathDelayMaxDeltaMicroseconds |
|P_RFC[RFC-to-be]_Seconds_Max (TBD3) |(TBD7) |
+------------------------------------+-------------------------------+
|OWDelay_HybridType1_Passive_I |pathDelaySumDeltaMicroseconds |
|P_RFC[RFC-to-be]_Seconds_Sum (TBD4) |(TBD8) |
+------------------------------------+-------------------------------+
Table 1: Mapping Between IPFIX IEs and Performance Metrics
]]></artwork>
</figure></t>
<t>Assuming time synchronization on devices, the delay is measured by
calculating the difference between the timestamp imposed with On-Path
Telemetry in the packet at the OAM encapsulation node and the timestamp
exported in the IPFIX flow record from the OAM transit and decapsulation
nodes. The lowest, highest, mean, and/or the sum of measured path delay
can be exported, thanks to the different IPFIX IE specifications.</t>
<figure anchor="topology"
title="Delay use case. Packets flow from host 1 to host 2.">
<artwork align="center"><![CDATA[
On-Path Telemetry Domain
.........................................
. .
. D1 .
. x------> .
. .
. D2 .
. x--------------------> .
. .
. D3 .
. x-----------------------------------> .
. .
(H1) ------ (R1) ------- (R2) ------- (R3) -------- (R4) ------ (H2)
Host 1 Encapsulation Transit Transit Decapsulation Host 2
Node Node 1 Node 2 Node
. .
. .
.........................................
]]></artwork>
</figure>
<t>In the usecase shown in <xref target="topology"/> using On-path
Telemetry to export the delay metrics, the node R2 exports the delay D1,
the node R3 exports the delay D2 and the decapsulation node R4 exports
the total delay D3 using IPFIX.</t>
<t>The advantages of this solution is that the delay metrics (min, max,
and mean) can be computed on the router, and aggregated directly within
the Flow Record, saving export bandwidth and computation on the Collector.
For the computation of the min, max, and mean delay metric, to be computed
locally on the router, the exporter Metering Process require some local caching/processing computation (for each new packets in the flow), specifically the mean value.
A less computational heavy solution for the router is the export of the delay
sum instead of the delay mean; on the Collector, the delay mean can easily be
computed by a single division operation (using the packet count). The alternative, w
ith any delay monitoring on the router, requires the export of every single packet as a separate Flow Record, including the timestamps information, for the Collector to compute delay metrics (min, max, and mean) and the recompute the aggregated Flow Record.</t>
</section>
<section anchor="notation" title="Terminology">
<t>The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP 14
<xref target="RFC2119"/> <xref target="RFC8174"/> when, and only when,
they appear in all capitals, as shown here.</t>
<t>This document makes use of the terms defined in <xref
target="RFC7011"/> and <xref target="RFC9378"/>.</t>
<t>The following terms are used as defined in <xref
target="RFC7011"/>:</t>
<t><list style="symbols">
<t>IPFIX</t>
<t>IPFIX Information Elements (IEs)</t>
<t>Flow</t>
<t>Flow Record</t>
<t>Exporter</t>
</list></t>
<t>The following terms are used as defined in <xref
target="RFC8911"/>:</t>
<t><list style="symbols">
<t>Performance Metric</t>
<t>Registered Performance Metric</t>
<t>Performance Metrics Registry</t>
</list></t>
<t>The following terms are used as defined in Section 5 of <xref
target="I-D.ietf-opsawg-oam-characterization"/>:</t>
<t><list style="symbols">
<t>Encapsulation node</t>
<t>Transit node</t>
<t>Decapsulation node</t>
</list></t>
</section>
<section anchor="PM" title="Performance Metrics">
<t>This section defines the new performance metrics following the
template defined in Section 11 of <xref target="RFC8911"/>.</t>
<t>IANA Note (to be removed): RFC 8192 Section 4 was taken a guiding
example.</t>
<section anchor="ip-ow-delay-hybridtype1-passive-reg-entries"
title="IP One-Way Delay Hybrid Type I Passive Performance Metrics">
<t>This section specifies four performance metrics for the Hybrid Type
I Passive assessment of IP One-Way Delay, to be registered in the
<xref target="IANA-PERF-METRIC">"IANA Performance Metric
Registry</xref>.</t>
<t>All column entries besides the Identifier, Name, URI, Description,
Output, and Reference Method categories are the same; thus, this section
defines four closely related performance metrics. As a result, IANA
has assigned corresponding URIs to each of the four registered
performance metrics.</t>
<section numbered="true" title="Summary">
<t>This category includes multiple indexes of the registered
performance metrics: the element Identifier and Metric Name.</t>
<section title="ID (Identifier)">
<t>IANA has allocated the numeric Identifiers TBD1, TBD2, TBD3,
and TBD4 for the four Named Metric Entries in the following
section.</t>
<t>RFC EDITOR NOTE: please replace TBD1, TBD2, TBD3, and TBD4.</t>
</section>
<section title="Name">
<t>TBD1:
OWDelay_HybridType1_Passive_IP_RFC[RFC-to-be]_Seconds_Mean</t>
<t>TBD2:
OWDelay_HybridType1_Passive_IP_RFC[RFC-to-be]_Seconds_Min</t>
<t>TBD3:
OWDelay_HybridType1_Passive_IP_RFC[RFC-to-be]_Seconds_Max</t>
<t>TBD4:
OWDelay_HybridType1_Passive_IP_RFC[RFC-to-be]_Seconds_Sum</t>
<t>RFC EDITOR NOTE: please replace [RFC-to-be].</t>
</section>
<section title="URI">
<t>URI: <eref
target="https://www.iana.org/assignments/performance-metrics/OWDelay_HybridType1_Passive_IP_RFC[RFC-to-be]_Seconds_Mean"/></t>
<t>URI: <eref
target="https://www.iana.org/assignments/performance-metrics/OWDelay_HybridType1_Passive_IP_RFC[RFC-to-be]_Seconds_Min"/></t>
<t>URI: <eref
target="https://www.iana.org/assignments/performance-metrics/OWDelay_HybridType1_Passive_IP_RFC[RFC-to-be]_Seconds_Max"/></t>
<t>URI: <eref
target="https://www.iana.org/assignments/performance-metrics/OWDelay_HybridType1_Passive_IP_RFC[RFC-to-be]_Seconds_Sum"/></t>
<t>RFC EDITOR NOTE: please replace TBD1, TBD2, TBD3, and TBD4.</t>
</section>
</section>
<section title="Description">
<t><list style="symbols">
<t>OWDelay_HybridType1_Passive_IP_RFC[RFC-to-be]_Seconds_Mean:
This metric assesses the mean of one-way delays of all
successfully forwarded IP packets constituting a single Flow. We
consider the measurement of one-way delay based on a single
Observation Point (OP) [RFC7011] somewhere in the network.</t>
<t>OWDelay_HybridType1_Passive_IP_RFC[RFC-to-be]_Seconds_Min:
This metric assesses the minimum of one-way delays of all
successfully forwarded IP packets constituting a single Flow. We
consider the measurement of one-way delay based on a single
Observation Point (OP) [RFC7011] somewhere in the network.</t>
<t>OWDelay_HybridType1_Passive_IP_RFC[RFC-to-be]_Seconds_Max:
This metric assesses the maximum of one-way delays of all
successfully forwarded IP packets constituting a single Flow. We
consider the measurement of one-way delay based on a single
Observation Point (OP) [RFC7011] somewhere in the network.</t>
<t>OWDelay_HybridType1_Passive_IP_RFC[RFC-to-be]_Seconds_Sum:
This metric assesses the sum of one-way delays of all
successfully forwarded IP packets constituting a single Flow. We
consider the measurement of one-way delay based on a single
Observation Point (OP) [RFC7011] somewhere in the network.</t>
</list></t>
</section>
<section title="Change Controller">
<t>IETF</t>
</section>
<section title="Version of Registry Format">
<t>1.0</t>
</section>
</section>
<section title="Metric Definition">
<t>This category includes columns to prompt the entry of all necessary
details related to the metric definition, including the immutable
document reference and values of input factors, called "Fixed
Parameters".</t>
<section title="Reference Definition">
<t>Almes, G., Kalidindi, S., Zekauskas, M., and A. Morton, Ed., "A
One-Way Delay Metric for IP Performance Metrics (IPPM)", STD 81, RFC
7679, DOI 10.17487/RFC7679, January 2016,
<https://www.rfc-editor.org/info/rfc7679>. <xref
target="RFC7679"/></t>
<t>Morton, A. and E. Stephan, "Spatial Composition of Metrics", RFC
6049, DOI 10.17487/RFC6049, January 2011,
<https://www.rfc-editor.org/info/rfc6049>. <xref
target="RFC6049"/></t>
<t>Section 3.4 of <xref target="RFC7679"/> provides the reference
definition of the singleton (single value) one-way delay metric.
Section 4.4 of <xref target="RFC7679"/> provides the reference
definition expanded to cover a multi-value sample. Note that terms
such as "singleton" and "sample" are defined in Section 2 of <xref
target="RFC2330"/>.</t>
<t>With the OP <xref target="RFC7011"/> typically located between
the hosts participating in the IP Flow, the one-way delay metric
requires one individual measurement between the OP and sourcing
host, such that the Spatial Composition <xref target="RFC6049"/> of
the measurements yields a one-way delay singleton.</t>
<t>This document specifies how to export the performance metric
using IPFIX.</t>
</section>
<section title="Fixed Parameters">
<t>None</t>
</section>
</section>
<section title="Method of Measurement">
<t>This category includes columns for references to relevant sections
of the RFC(s) and any supplemental information needed to ensure an
unambiguous method for implementations.</t>
<section title="Reference Methods">
<t>The foundational methodology for this metric is defined in
Section 4 of <xref target="RFC7323"/> using the Timestamps option
with modifications that allow application at a mid-path OP <xref
target="RFC7011"/>.</t>
</section>
<section title="Packet Stream Generation">
<t>The timestamp when the packet is being received at OAM
encapsulation node. Format depends on On-Path Telemetry
implementation. For IOAM, Section 4.4.1 of <xref target="RFC9197"/>
describes what kind of timestamps are supported. Section 4.4.2.3 and
4.4.2.4 describe where the timestamp is being inserted. For the
Enhanced Alternate Marking Method, Section 2 of <xref
target="I-D.zhou-ippm-enhanced-alternate-marking"/> describes
timestamp encoding and granularity.</t>
</section>
<section title="Traffic Filtering (Observation) Details">
<t>Runtime Parameters (in the following sections) may be used for
Traffic Filtering.</t>
</section>
<section title="Sampling Distribution">
<t>This metric requires a partial sample of all packets that qualify
according to the Traffic Filter criteria.</t>
</section>
<section title="Runtime Parameters and Data Format">
<t>Runtime Parameters are input factors that must be determined,
configured into a measurement system, and reported with the results
for the context to be complete.</t>
<t>The hybrid type I metering parameters must be reported to provide
the complete measurement context. As an example, if the IPFIX
Metering Process is used, then the IPFIX Metering Process parameters
(IPFIX Template Record, potential traffic filters, and potential
sampling method and parameters) that generate the Flow Records must
be reported to provide the complete measurement context. At a
minimum, the following fields are required:</t>
<t><list style="hanging">
<t hangText="Src:">The IP address of the host in the host A Role
(format ipv4&nbhy;address-no-zone value for IPv4 or
ipv6-address-no-zone value for IPv6; see Section 4 of <xref
target="RFC6991"/>).</t>
<t hangText="Dst:">The IP address of the host in the host B Role
(format ipv4&nbhy;address-no-zone value for IPv4 or
ipv6-address-no-zone value for IPv6; see Section 4 of <xref
target="RFC6991"/>).</t>
<t hangText="T0:">T time, the start of a measurement interval
(format "date/time" as specified in Section 5.6 of <xref
target="RFC3339"/>; see also "date-and-time" in Section 3 of
<xref target="RFC6991"/>). The UTC Time Zone is required by
Section 6.1 of <xref target="RFC2330"/>. When T0 is "all-zeros",
a start time is unspecified and Tf is to be interpreted as the
duration of the measurement interval. The start time is
controlled through other means.</t>
<t hangText="Tf:">A time, the end of a measurement interval
(format "date/time" as specified in Section 5.6 of <xref
target="RFC3339"/>; see also "date-and-time" in Section 3 of
<xref target="RFC6991"/>)). The UTC Time Zone is required by
Section 6.1 of <xref target="RFC2330"/>. When T0 is "all-zeros",
an ending time and date is ignored and Tf is interpreted as the
duration of the measurement interval.</t>
</list></t>
</section>
<section title="Roles">
<t><list style="hanging">
<t hangText="host A:">Launches an IP packet to start the
Flow.</t>
<t hangText="host B:">Receives the IP packet to start the
Flow.</t>
<t hangText="Encapsulation Node:">Receives the IP Flow packets
and encapsulates the timestamp into the packet.</t>
<t hangText="Transit Node:">Receives the IP Flow packets and
measures the delay between the timestamp in the packet and the
timestamp when the packet was received.</t>
<t hangText="Decapsulation Node:">Receives the IP Flow packets
and computes the delay between the timestamp in the packet and
the timestamp when the packet was received and removes the OAM
header from the packet.</t>
</list></t>
</section>
</section>
<section title="Output">
<t>This category specifies all details of the output of measurements
using the metric.</t>
<section title="Type">
<t>OWDelay Types are discussed in the subsections below.</t>
</section>
<section title="Reference Definition">
<t>For all output types:</t>
<t><list style="hanging">
<t hangText="OWDelay_HybridType1_Passive_IP:">The one-way delay
of one IP packet is a Singleton</t>
</list></t>
<t>For each <statistic> Singleton one of the following
subsections applies.</t>
<section title="OWDelay_HybridType1_Passive_IP_RFC[RFC-to-be]_Seconds_Mean">
<t>Similar to Section 7.4.2.2 of <xref target="RFC8912"/>, the mean
SHALL be calculated using the conditional distribution
of all packets with a finite value of one-way delay (undefined
delays are excluded) -- a single value, as follows:</t>
<t>See Section 4.1 of <xref target="RFC3393"/> for details on the
conditional distribution to exclude undefined values of delay, and
see Section 5 of <xref target="RFC6703"/> for background on this
analysis choice.</t>
<t>See Section 4.2.2 of <xref target="RFC6049"/> for details on
calculating this statistic; see also Section 4.2.3 of <xref
target="RFC6049"/>.</t>
<t><list style="hanging">
<t hangText="Mean:">The time value of the result is expressed
in units of seconds, as a positive value of type decimal64
with fraction digits = 9 (similar to the decimal64 in YANG,
Section 9.3 of <xref target="RFC6020"/>) with a resolution of
0.000000001 seconds (1.0 ns), and with lossless
conversion to/from the 64-bit NTP timestamp as per Section 6
of <xref target="RFC5905"/>.</t>
</list></t>
</section>
<section title="OWDelay_HybridType1_Passive_IP_RFC[RFC-to-be]_Seconds_Min">
<t>Similar to Section 7.4.2.3 of <xref target="RFC8912"/>, the
minimum SHALL be calculated using the conditional
distribution of all packets with a finite value of one-way delay
(undefined delays are excluded) -- a single value, as follows:</t>
<t>See Section 4.1 of <xref target="RFC3393"/> for details on the
conditional distribution to exclude undefined values of delay, and
see Section 5 of <xref target="RFC6703"/> for background on this
analysis choice.</t>
<t>See Section 4.3.2 of <xref target="RFC6049"/> for details on
calculating this statistic; see also Section 4.3.3 of <xref
target="RFC6049"/>.</t>
<t><list style="hanging">
<t hangText="Min:">The time value of the result is expressed
in units of seconds, as a positive value of type decimal64
with fraction digits = 9 (similar to the decimal64 in YANG,
Section 9.3 of <xref target="RFC6020"/>) with a resolution of
0.000000001 seconds (1.0 ns), and with lossless
conversion to/from the 64-bit NTP timestamp as per Section 6
of <xref target="RFC5905"/>.</t>
</list></t>
</section>
<section title="OWDelay_HybridType1_Passive_IP_RFC[RFC-to-be]_Seconds_Max">
<t>Similar to Section 7.4.2.4 of <xref target="RFC8912"/>, the
maximum SHALL be calculated using the conditional
distribution of all packets with a finite value of one-way delay
(undefined delays are excluded) -- a single value, as follows:</t>
<t>See Section 4.1 of <xref target="RFC3393"/> for details on the
conditional distribution to exclude undefined values of delay, and
see Section 5 of <xref target="RFC6703"/> for background on this
analysis choice.</t>
<t>See Section 4.3.2 of <xref target="RFC6049"/> for a closely
related method for calculating this statistic; see also Section
4.3.3 of <xref target="RFC6049"/>. The formula is as follows:</t>
<t><figure>
<artwork><![CDATA[
Max = (FiniteDelay[j])
such that for some index, j, where 1 <= j <= N
FiniteDelay[j] >= FiniteDelay[n] for all n
]]></artwork>
</figure></t>
<t>where all packets n = 1 through N have finite singleton
delays.</t>
<t><list style="hanging">
<t hangText="Max:">The time value of the result is expressed
in units of seconds, as a positive value of type decimal64
with fraction digits = 9 (similar to the decimal64 in YANG,
Section 9.3 of <xref target="RFC6020"/>) with a resolution of
0.000000001 seconds (1.0 ns), and with lossless
conversion to/from the 64-bit NTP timestamp as per Section 6
of <xref target="RFC5905"/>.</t>
</list></t>
</section>
<section title="OWDelay_HybridType1_Passive_IP_RFC[RFC-to-be]_Seconds_Sum">
<t>The sum SHALL be calculated using the conditional distribution
of all packets with a finite value of one-way delay (undefined
delays are excluded) -- a single value, as follows:</t>
<t>See Section 4.1 of <xref target="RFC3393"/> for details on the
conditional distribution to exclude undefined values of delay, and
see Section 5 of <xref target="RFC6703"/> for background on this
analysis choice.</t>
<t>See Section 4.3.5 of <xref target="RFC6049"/> for details on
calculating this statistic. However in this case FiniteDelay or
MaxDelay MAY be used.</t>
<t><list style="hanging">
<t hangText="Sum:">The time value of the result is expressed
in units of seconds, as a positive value of type decimal64
with fraction digits = 9 (similar to the decimal64 in YANG,
Section 9.3 of <xref target="RFC6020"/>) with a resolution of
0.000000001 seconds (1.0 ns), and with lossless
conversion to/from the 64-bit NTP timestamp as per Section 6
of <xref target="RFC5905"/>.</t>
</list></t>
</section>
<section title="Metric Units">
<t><list style="symbols">
<t>Mean</t>
<t>Min</t>
<t>Max</t>
<t>Sum</t>
</list></t>
<t>The one-way delay of the IP Flow singleton is expressed in
seconds.</t>
</section>
<section title="Calibration">
<t>Passive Measurements at an OP could be calibrated against an
Active Measurement at host A where the Active Measurement
represents the ground truth.</t>
</section>
</section>
<section title="Administrative Items">
<section title="Status">
<t>Current</t>
</section>
<section title="Requester">
<t>This RFC</t>
<t>RFC EDITOR NOTE: please replace This RFC text by the RFC issued
from this document</t>
</section>
<section title="Revision">
<t>1.0</t>
</section>
<section title="Revision Date">
<t>RFC Date</t>
</section>
</section>
<section title="Comments and Remarks">
<t>none</t>
</section>
</section>
</section>
<section anchor="IE" title="IPFIX Information Elements">
<t>This section specifies the follwing new IPFIX IEs:<list
style="hanging">
<t hangText="pathDelayMeanDeltaMicroseconds"><vspace
blankLines="0"/> 32-bit unsigned integer that identifies the mean
path delay of all packets in the Flow, in microseconds, between the
OAM encapsulation node and the local node with the OAM domain
(either an OAM transit node or an OAM decapsulation node).</t>
<t hangText="pathDelayMinDeltaMicroseconds"><vspace blankLines="0"/>
32-bit unsigned integer that identifies the lowest path delay of all
packets in the Flow, in microseconds, between the OAM encapsulation
node and the local node with the OAM domain (either an OAM transit
node or an OAM decapsulation node).</t>
<t hangText="pathDelayMaxDeltaMicroseconds"><vspace blankLines="0"/>
32-bit unsigned integer that identifies the highest path delay of
all packets in the Flow, in microseconds, between the OAM
encapsulation node and the local node with the OAM domain (either an
OAM transit node or an OAM decapsulation node).</t>
<t hangText="pathDelaySumDeltaMicroseconds"><vspace blankLines="0"/>
64-bit unsigned integer that identifies the sum of the path delay of
all packets in the Flow, in microseconds, between the OAM
encapsulation node and the local node with the OAM domain (either an
OAM transit node or an OAM decapsulation node).</t>
</list></t>
</section>
<section anchor="Use-Cases" title="Use Cases">
<t>The measured On-Path delay can be aggregated with Flow Aggregation as
defined in <xref target="RFC7015"/> to the following device and
control-plane dimensions to determine:</t>
<t><list style="symbols">
<t>With node id and egressInterface(14), on which node which logical
egress interfaces have been contributing to how much delay.</t>
<t>With node id and egressPhysicalInterface(253), on which node
which physical egress interfaces have been contributing to how much
delay.</t>
<t>With ipNextHopIPv4Address(15) or ipNextHopIPv6Address(62), the
forwarding path to which next-hop IP contributed to how much
delay.</t>
<t>With mplsTopLabelIPv4Address(47) or destinationIPv6Address and
srhActiveSegmentIPv6(495), the forwarding path to which MPLS top
label IPv4 address or IPv6 destination address and SRv6 active
segment contributed to how much delay.</t>
<t>BGP communities <xref target="RFC1997"/> are often used for
setting a path priority or service selection. With
bgpDestinationExtendedCommunityList(488) or
bgpDestinationCommunityList(485) or
bgpDestinationLargeCommunityList(491) which group of prefixes
accumulated at which node how much delay.</t>
<t>With destinationIPv4Address(13), destinationTransportPort(11),
protocolIdentifier (4) and sourceIPv4Address(8), or equivalent IPFIX
IEs for IPv6, the forwarding path delay on each node from each IPv4
source address to a specific application in the network.</t>
</list></t>
<t>Let us consider the example depicted in Figure 1 from Section 1 as
topology example. Below example table shows the aggregated delay per
each node, ingressInterface,(10) egressInterface(14),
destinationIPv6Address(28) and srhActiveSegmentIPv6(495).</t>
<t><figure>
<artwork><![CDATA[
+-----------+-----------+------+-------------+-------------+------------+
| ingress | egress | Node | destination | srhActive | Path Delay |
| Interface | Interface | | IPv6Address | SegmentIPv6 | |
+-----------+-----------+------+-------------+-------------+------------+
| 271 | 276 | R1 | 2001:db8::2 | 2001:db8::4 | 0 us |
+-----------+-----------+------+-------------+-------------+------------+
| 301 | 312 | R2 | 2001:db8::3 | 2001:db8::4 | 22 us |
+-----------+-----------+------+-------------+-------------+------------+
| 22 | 27 | R3 | 2001:db8::4 | 2001:db8::4 | 42 us |
+-----------+-----------+------+-------------+-------------+------------+
| 852 | 854 | R4 | 2001:db8::4 | 2001:db8::4 | 122 us |
+-----------+-----------+------+-------------+-------------+------------+
Table 2: Example table of measured delay. Ascending by delay.
]]></artwork>
</figure></t>
</section>
<section anchor="IANA" title="IANA Considerations">
<section anchor="PM-IANA" title="Performance Metrics">
<t>This document requests IANA to add four new performance metrics
under the "Performance Metrics" registry <xref target="RFC8911"/> with
the four templates defined in Section 3.</t>
</section>
<section anchor="IE-IANA" title="IPFIX Entities">
<t>This document requests IANA to register new IPFIX IEs (see table 3)
under the "IPFIX Information Elements" registry <xref
target="RFC7012"/> available at <xref target="IANA-IPFIX">"IANA IP
Flow Information Export (IPFIX) Entities Registry</xref> and assign
the following initial code points.</t>
<t><figure>
<artwork><![CDATA[
+-------+--------------------------------+
|Element| Name |
| ID | |
+-------+--------------------------------+
| TBD5 | pathDelayMeanDeltaMicroseconds |
| | |
+-------+--------------------------------+
| TBD6 | pathDelayMinDeltaMicroseconds |
| | |
+-------+--------------------------------+
| TBD7 | pathDelayMaxDeltaMicroseconds |
| | |
+-------+--------------------------------+
| TBD8 | pathDelaySumDeltaMicroseconds |
| | |
+-------+--------------------------------+
Table 3: New IPFIX IEs in the "IPFIX Information Elements" Registry
]]></artwork>
</figure></t>
<t>Note to the RFC-Editor:</t>
<t><list style="symbols">
<t>Please replace TBD5 - TBD8 with the values allocated by
IANA</t>
<t>Please replace all instances of [RFC-to-be] in this section
with the RFC number assigned to this document</t>
</list></t>
<section anchor="IANApathDelayMeanDeltaMicroseconds"
title="pathDelayMeanDeltaMicroseconds">
<dl>
<dt>Name:</dt>
<dd>pathDelayMeanDeltaMicroseconds</dd>
</dl>
<dl>
<dt>ElementID:</dt>
<dd>TBD5</dd>
</dl>
<dl>
<dt>Description:</dt>
<dd>This Information Element identifies the mean path delay of all
packets in the Flow, in microseconds, between the OAM
encapsulation node and the local node with the OAM domain (either
an OAM transit node or an OAM decapsulation node), according to
OWDelay_HybridType1_Passive_IP_RFC[RFC-to-be]_Seconds_Mean in the
IANA Performance Metric Registry</dd>
</dl>
<dl>
<dt>Abstract Data Type:</dt>
<dd>unsigned32</dd>
</dl>
<dl>
<dt>Data Type Semantics:</dt>
<dd>deltaCounter</dd>
</dl>
<dl>
<dt>Reference:</dt>
<dd>[RFC-to-be],
OWDelay_HybridType1_Passive_IP_RFC[RFC-to-be]_Seconds_Mean in the
IANA Performance Metric Registry.</dd>
</dl>
</section>
<section anchor="IANApathDelayMinDeltaMicroseconds"
title="pathDelayMinDeltaMicroseconds">
<dl>
<dt>Name:</dt>
<dd>pathDelayMinDeltaMicroseconds</dd>
</dl>
<dl>
<dt>ElementID:</dt>
<dd>TBD6</dd>
</dl>
<dl>
<dt>Description:</dt>
<dd>This Information Element identifies the lowest path delay of
all packets in the Flow, in microseconds, between the OAM
encapsulation node and the local node with the OAM domain (either
an OAM transit node or an OAM decapsulation node), according to
the OWDelay_HybridType1_Passive_IP_RFC[RFC-to-be]_Seconds_Min in
the IANA Performance Metric Registry.</dd>
</dl>
<dl>
<dt>Abstract Data Type:</dt>
<dd>unsigned32</dd>
</dl>
<dl>
<dt>Data Type Semantics:</dt>
<dd>deltaCounter</dd>
</dl>
<dl>
<dt>Reference:</dt>
<dd>[RFC-to-be],
OWDelay_HybridType1_Passive_IP_RFC[RFC-to-be]_Seconds_Min in the
IANA Performance Metric Registry.</dd>
</dl>
</section>
<section anchor="IANApathDelayMaxDeltaMicroseconds"
title="pathDelayMaxDeltaMicroseconds">
<dl>
<dt>Name:</dt>
<dd>pathDelayMaxDeltaMicroseconds</dd>
</dl>
<dl>
<dt>ElementID:</dt>
<dd>TBD7</dd>
</dl>
<dl>
<dt>Description:</dt>
<dd>This Information Element identifies the highest path delay of
all packets in the Flow, in microseconds, between the OAM
encapsulation node and the local node with the OAM domain (either
an OAM transit node or an OAM decapsulation node), according to
OWDelay_HybridType1_Passive_IP_RFC[RFC-to-be]_Seconds_Max in the
IANA Performance Metric Registry.</dd>
</dl>
<dl>
<dt>Abstract Data Type:</dt>
<dd>unsigned32</dd>
</dl>
<dl>
<dt>Data Type Semantics:</dt>
<dd>deltaCounter</dd>
</dl>
<dl>
<dt>Reference:</dt>
<dd>[RFC-to-be],
OWDelay_HybridType1_Passive_IP_RFC[RFC-to-be]_Seconds_Max in the
IANA Performance Metric Registry.</dd>
</dl>
</section>
<section anchor="IANApathDelaySumDeltaMicroseconds"
title="pathDelaySumDeltaMicroseconds">
<dl>
<dt>Name:</dt>
<dd>pathDelaySumDeltaMicroseconds</dd>
</dl>
<dl>
<dt>ElementID:</dt>
<dd>TBD8</dd>
</dl>
<dl>
<dt>Description:</dt>
<dd>This Information Element identifies the sum of the path delay
of all packets in the Flow, in microseconds, between the OAM
encapsulation node and the local node with the OAM domain (either
an OAM transit node or an OAM decapsulation node), according to
OWDelay_HybridType1_Passive_IP_RFC[RFC-to-be]_Seconds_Sum in the
IANA Performance Metric Registry.</dd>
</dl>
<dl>
<dt>Abstract Data Type:</dt>
<dd>unsigned64</dd>
</dl>
<dl>
<dt>Data Type Semantics:</dt>
<dd>deltaCounter</dd>
</dl>
<dl>
<dt>Reference:</dt>
<dd>[RFC-to-be],
OWDelay_HybridType1_Passive_IP_RFC[RFC-to-be]_Seconds_Sum in the
IANA Performance Metric Registry.</dd>
</dl>
</section>
</section>
</section>
<section anchor="Operational" title="Operational Considerations">
<section anchor="OpsTimeAccuracy" title="Time Accuracy">
<t>The same recommendation as defined in Section 4.5 of <xref
target="RFC5153"/> for IPFIX applies in terms of clock precision to
this document as well.</t>
</section>